Sexual dimorphism in a Late Ordovician caryocaridid (Malacostraca, Phyllocarida) identified by carapace geometric morphometrics

Liu, Yilong 1 ; Hegna, Thomas A.2; Liu, Yi-ting1; Fan, Ruo-ying1; Zong, Rui-wen 1 ; Gong, Yi-ming1

Published Jan 22, 2026 on Dryad. https://doi.org/10.5061/dryad.7h44j1087

Data files

Jan 22, 2026 version files 480.64 MB

caryocaridid_measurements.csv

5.11 KB
Fig._S1.tif

101.10 MB
Fig._S2.tif

259.37 MB
Fig._S3.tif

73.04 MB
Fig._S4.tif

43.77 MB
Liu_et_al.---Paleobiology---Supplemental_Material.pdf

3.36 MB
README.md

2.92 KB

Abstract

This dataset contains morphometric measurements of 95 caryocaridid phyllocarid carapaces (Soomicaris ordosensis) from the Upper Ordovician (Katian) Lashizhong Formation of North China. Parameters include height, length, anterior-horn angle, projected area and perimeter obtained via geometric morphometrics. Three carapace types (T1–T3) were distinguished and are provided together with raw TIFF images of modern analogues, stratigraphic columns and PCA results. The data support the accepted article in Paleobiology and can be reused for evolutionary, biogeographic or taxonomic studies of Paleozoic phyllocarids.

1. Brief description

This dataset contains morphometric measurements of Soomicaris ordosensis carapaces from the Upper Ordovician of the North China and Tarim plates, associated with the accepted article in Paleobiology (2025). Three carapace types (T1–T3) were distinguished based on geometric morphometrics.

2. File list

File name	Description
`caryocaridid_measurements.csv`	Raw measurements for 95 specimens (see Variables below).
`Fig_S1.tif`	Figure S1 – sexual dimorphism in modern leptostracans.
`Fig_S2.tif`	Figure S2 – palaeogeographical & geological maps.
`Fig_S3.tif`	Figure S3 – PCA factor loadings.
`Fig_S4.tif`	Figure S4 – shape vs size scatter plot.
`Liu_et_al_Paleobiology_SuppMaterial.pdf`	Full original Supplemental Material (text + figures + table).

3. Variables in CSV

Column	Unit	Description
`specimen_id`	—	Original specimen label (e.g., T1-WHJ-3-1).
`type`	—	Carapace type (T1, T2, T3).
`H_m`	mm	Measured height.
`H_o`	mm	Original height (after taphonomic correction).
`L`	mm	Measured length.
`L_H_o`	—	Length / original height ratio.
`alpha`	°	Angle of the anterior horn of carapace.
`area`	mm²	2-D projected area.
`perimeter`	mm	2-D projected perimeter.

4. Software & scripts

R ≥ 4.2 required; packages: geomorph, tidyverse, Morpho.
PCA & shape analysis code available on GitHub: https://github.com/yourhandle/caryocaridid_morphometrics (will be made public upon publication).

5. Geographic & stratigraphic context

Wuhai area, Inner Mongolia (North China Plate) – Lashizhong Fm.
Kuruktagh area, Xinjiang (Tarim Plate) – Queerqueke Fm.
Both formations: Upper Ordovician (Katian).

Files in this dataset

caryocaridid_measurements.csv – Tabular morphometric data (95 specimens).
Liu_et_al.---Paleobiology---Supplemental_Material.pdf – Original combined supplemental text and figures.
Fig._S1.tif – Sexual dimorphism in modern leptostracans
Fig._S2.tif – Palaeogeographical & geological maps.
Fig._S3.tif – PCA factor loadings.
Fig._S4.tif – Shape vs size scatter plot.